BUGFIX: Fix content cache for discard, revert #5083 for now

[mhsdesign]

Resolves: https://github.com/neos/neos-development-collection/issues/5150

Readds the contentstreamid to node cache entry identifier (effectively reverting the changes in #5083 conceptional)

The change was taken too lightly and the whole content cache flushing depends on the assumption that after publishing or discard, everything will be rendered. With this knowledge and the added test we should be able to refactor it correctly in the feature without introducing a regression again.

The regression #5150 was attempted to be fixed in several ways https://github.com/neos/neos-development-collection/pull/5155 or https://github.com/neos/neos-development-collection/pull/5160 but it seems we need more brain power to finish this. For the meantime this pr restores the behaviour again and lets us continue development in the Neos Ui with green e2e tests.

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• [ ] Code follows the PSR-2 coding style
• [ ] Tests have been created, run and adjusted as needed
• [ ] The PR is created against the lowest maintained branch
• [ ] Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• [ ] Reviewer - The first section explains the change briefly for change-logs
• [ ] Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[kitsunet]

Unfortunate, but yeah probably one of those hard problems.

[mhsdesign]

The Neos Ui e2e tests also work locally with this change again.